Dye composition for keratin fibers, with a cationic direct dye and a polyol or polyol ether

ABSTRACT

The invention relates to a dye composition for keratin fibers, in particular for human keratin fibers such as the hair, comprising at least one cationic direct dye of given formula and at least glycerol and/or one specific polyol and/or polyol ether. The invention also relates to the dyeing processes and devices using this composition.

[0001] The invention relates to a dye composition for keratin fibers, inparticular for human keratin fibers such as the hair, comprising, in amedium which is suitable for dyeing, at least one cationic direct dye ofgiven formula, and at least glycerol and/or one specific polyol and/orpolyol ether.

[0002] The invention also relates to the dyeing processes and devicesusing the composition.

[0003] Two types of coloration can be distinguished in the field of hairtreatment.

[0004] The first is semi-permanent or temporary dyeing, or directdyeing, which involves dyes capable of giving the hair's natural color amore or less pronounced color change which may withstand shampooingseveral times. These dyes are known as direct dyes; they can be usedwith or without an oxidizing agent. In the presence of an oxidizingagent, the aim is to obtain a lightening coloration. The lighteningcoloration is carried out by applying to the hair the mixture, preparedat the time of use, of a direct dye and an oxidizing agent, and inparticular makes it possible to obtain, by lightening the melanin in thehair, an advantageous effect such as a unified color in the case of greyhair, or to bring out the color in the case of naturally pigmented hair.

[0005] The second is permanent dyeing or oxidation dyeing. This iscarried out with dyes known as “oxidation” dyes comprising oxidation dyeprecursors and couplers. Oxidation dye precursors, commonly known as“oxidation bases”, are initially colorless or weakly colored compoundswhich develop their dyeing power on the hair in the presence ofoxidizing agents added at the time of use, leading to the formation ofcolored compounds and dyes. The formation of these colored compounds anddyes results either from an oxidative condensation of the “oxidationbases” with themselves or from an oxidative condensation of the“oxidation bases” with coloration modifier compounds commonly known as“couplers”, which are generally present in the dye compositions used inoxidation dyeing.

[0006] In order to vary the shades obtained with the said oxidationdyes, or to enrich them with glints, it is known to add direct dyesthereto.

[0007] Among the cationic direct dyes available in the field of dyeingkeratin fibers, in particular human keratin fibers, compounds which arealready known are those whose structure is developed in the text whichfollows; nevertheless, these dyes lead to colorations which haveproperties that are still insufficient, e.g., the homogeneity of thecolor distributed along the fiber (“unison”), in which case it is saidthat the coloration is too selective, the staying power, in terms ofresistance to the various attacking factors to which the hair may besubjected (light, bad weather, shampooing) and the intensity.

[0008] After considerable research conducted in this matter, theinventors have now discovered that it is possible to obtain novelcompositions for dyeing keratin fibers, which are capable of leading tocolorations which can be more resistant to the various attacking factorsto which the hair may be subjected, and can be more intense and lessselective, by combining at least glycerol and/or one specific polyolandlor polyol ether with at least one cationic direct dye known in theprior art, and of formula (I) defined below.

[0009] This discovery forms the basis of the present invention.

[0010] A first subject of the present invention is thus a compositionfor dyeing keratin fibers, and in particular human keratin fibers suchas the hair, containing, in a medium which is suitable for dyeing, (i)at least one cationic direct dye whose structure corresponds to formula(I) below, characterized in that it also contains (ii) at least glyceroland/or one specific polyol and/or polyol ether.

[0011] (i) The cationic direct dye which can be used according to thepresent invention is a compound of formula (I) below:

A—B═N—B  (I)

[0012] in which:

[0013] the symbol A represents a group chosen from structures A₁ to A₃below:

[0014] in which structures A₁ to A₃,

[0015] R, is chosen from C₁-C₄ alkyl radicals and a phenyl radicalhaving a substituent chosen from C₁-C₄ alkyl radicals and halogen atomschosen from chlorine, bromine, iodine and fluorine;

[0016] R₂ is chosen from C₁-C₄ alkyl radicals and a phenyl radical;

[0017] R₃ and R₄, which may be identical or different, are chosen fromC₁-C₄ alkyl radicals and a phenyl radical or, in the case of structureA₁, can together form a substituted benzene ring, and in the case ofstructure A₂, can together form a benzene ring optionally having atleast one substituent chosen from C₁-C₄ alkyl, C₁-C₄ alkoxy and NO₂radicals;

[0018] R₃ can ailso denote a hydrogen atom;

[0019] Z is chosen from an oxygen atom, a sulphur atom, and —NR₂ groups;

[0020] M is chosen from —CH, —CR, where R is chosen from C₁-C₄ alkylradicals, and —N⁺R₅(X⁻)_(r) groups;

[0021] K is chosen from —CH, —CR, where R is chosen from C₁-C₄ alkylradicals, and —N⁺R₅(X⁻)_(r) groups;

[0022] P is chosen from —CH, —CR, where R is chosen from C₁-C₄ alkylradicals, and —N⁺R₅(X⁻)_(r) groups;

[0023] r denotes 0 or 1;

[0024] R₅ is chosen from an atom O⁻, C₁-C₄ alkoxy radicals and C₁-C₄alkyl radicals;

[0025] R₆ and R₇, which may be identical or different, are chosen from ahydrogen atom, halogen atoms chosen from chlorine, bromine, iodine andfluorine, C₁-C₄ alkyl radicals, C₁-C₄ alkoxy radicals and an —NO₂radical;

[0026] X⁻ is an anion, preferably chosen from chloride, iodide, methylsulphate, ethyl sulphate, acetate and perchlorate;

[0027] with the proviso that,

[0028] if R₄ is a C₁-C₄ alkyl radical and Z is a sulphur atom, R₃ is nota hydrogen atom;

[0029] if R₅ is O⁻, then r is zero;

[0030] if K or P or M is —N⁺—C₁-C₄ -alkyl X⁻, then R₆ or R₇ is otherthan a hydrogen atom;

[0031] if K is −N⁺R₅(X⁻)_(r), then M═P and is —CH or —CR;

[0032] if M is —N⁺R₅(X⁻)_(r), then K═P and is —CH or —CR;

[0033] if P is —N⁺R₅(X⁻)_(r), then K═M and is —CH or —CR;

[0034] if Z is —NR₂ and R₂ is a C₁-C₄ alkyl radical, then at least oneof the radicals R₁, R₃ or R₄ of structure A₂ is other than a C₁-C₄ alkylradical;

[0035] the symbol B represents:

[0036] (a) a group of structure B₁ below:

[0037] in which structure B₁,

[0038] R₈ is chosen from a hydrogen atom, halogen atoms chosen fromchlorine, bromine, iodine and fluorine, C₁-C₄ alkyl radicals, C₁-C₄alkoxy radicals, a radical —OH, a radical —NO₂, —NHR₁₁ radicals,—NR₁₂R₁₃ radicals, and —NHCO(C₁-C₄)alkyl radicals or forms, with R₉, a5- or 6-membered ring which may contain at least one hetero atom chosenfrom nitrogen, oxygen and sulphur;

[0039] R₉ is chosen from a hydrogen atom, halogen atoms chosen fromchlorine, bromine, iodine and fluorine, C₁-C₄ alkyl radicals, and C₁-C₄alkoxy radicals, or forms, with R₁₀ or R₁₁, a 5- or 6-membered ringwhich may contain at least one hetero atom chosen from nitrogen, oxygenand sulphur;

[0040] R₁₀ is chosen from a hydrogen atom, an —OH radical, —NHR₁₁radicals and —NR₁₂R₁₃ radicals;

[0041] R₁₁ is chosen from a hydrogen atom, C₁-C₄ alkyl radicals, C₁-C₄monohydroxyalkyl radicals, C₂-C₄ polyhydroxyalkyl radicals and a phenylradical;

[0042] R₁₂ and R₁₃, which may be identical or different, are chosen fromC₁-C₄ alkyl radicals, C₁-C₄ monohydroxyalkyl radicals and C₂-C₄polyhydroxyalkyl radicals; or

[0043] (b) a 5- or 6-membered nitrogenous heterocyclic group which cancontain at least one other hetero atom and/or at least one carbonylgroup and which can have at least one substituent chosen from C₁-C₄alkyl, amino and phenyl radicals, and in particular a group of structureB2 below:

[0044] in which structure B2, R₁₄ and R₁₅, which may be identical ordifferent, are chosen from a hydrogen atom and C₁-C₄ alkyl and phenylradicals;

[0045] Y denotes a —CO— radical or a radical

[0046] n=0 or 1, where, when n denotes 1, U denotes a —CO— radical.

[0047] In the structures defined above, the C₁-C₄ alkyl or alkoxy grouppreferably denotes methyl, ethyl, butyl, methoxy or ethoxy.

[0048] The cationic direct dyes of formula (I) which can be used in thedye compositions in accordance with the invention are known compoundsand are described, for example, in patent applications FR-2,189,006,FR-2,285,851 and FR-2,140,205 and its Certificates of Addition, thedisclosures of all of which are specifically incorporated by referenceherein.

[0049] Among the cationic direct dyes of formula (I) which can be usedin the dye compositions in accordance with the invention, those offormula (I) in which the symbol A denotes structure A3 while the symbolB denotes structure B1 or B2 are particularly preferred.

[0050] Among these compounds, mention may especially be made moreparticularly of the compounds of structures (I)₁ to (II)₇₇ below:

[0051] The cationic direct dye(s) used according to the inventionpreferably represent(s) from 0.001 to 10% by weight approximatelyrelative to the total weight of the dye composition, and even morepreferably from 0.005 to 5% by weight approximately relative to thisweight.

[0052] (ii) For the purposes of the invention, the term “polyol” denotesa compound of linear, branched or cyclic, saturated or unsaturated alkyltype bearing at least two —OH functions on the alkyl chain, as well asthe polymers (polyethers) of these polyhydroxyalkyl compounds.

[0053] The specific polyols used according to the invention contain atleast 4 carbon atoms and can be chosen in particular from C₄-C₉ polyolsand polyalkylene glycols such as, more particularly, polyethyleneglycols and polypropylene glycols.

[0054] Among the C₄-C₉ polyols, mention may be made in particular of2-butene-1,4-diol, pentane-1,5-diol, 2,2-dimethylpropane-1,3-diol,3-methylpentane-1,5-diol, pentane-1,2-diol,2,2,4-trimethylpentane-1,3-diol, 2-methylpropane-1,3-diol, hexyleneglycol, 1,3-butylene glycol, dipropylene glycol, diethylene glycol andtriethylene glycol.

[0055] The specific polyol ethers according to the invention are chosenfrom C₁-C₈ aliphatic ethers of C₃-C₉ polyols and C₆-C₈ aromatic ethersof C₂-C₉ polyols.

[0056] Among the C₁-C₈ aliphatic ethers of C₃-C₉ polyols, mention may bemade in particular of propylene glycol monomethyl ether, propyleneglycol monoethyl ether, isopropylene glycol dimethyl ether, diethyleneglycol monomethyl ether and monoethyl ether, dipropylene glycolmonomethyl ether, tripropylene glycol monomethyl ether and diethyleneglycol dimethyl ether;

[0057] among the C₆-C₈ aromatic ethers of C₂-C₉ polyols, mention may bemade in particular of ethylene glycol monophenyl ether, ethylene glycolmonobenzyl ether, propylene glycol monophenyl ether, propylene glycolmonobenzyl ether, diethylene glycol monophenyl ether and diethyleneglycol monobenzyl ether.

[0058] The glycerol and/or the polyol(s) and/or polyol ether(s)described for the purposes of the invention are present in the dyecomposition in accordance with the invention in proportions generallyranging from 0.1 to 40% by weight, and even more particularly from 0.5to 20% by weight, relative to the total weight of the composition.

[0059] The medium which is suitable for dyeing (or support) generallycomprises a mixture of water and at least glycerol and/or a polyoland/or polyol ether as defined above. It can also contain one or moreorganic solvents other than glycerol and/or the polyol(s) and/or polyolether(s) used in accordance with the invention, to dissolve thecompounds which would not be sufficiently soluble in water. Organicsolvents which may be mentioned, for example, are C₁-C₄ alkanols such asethanol and isopropanol, as well as aromatic alcohols such as benzylalcohol, similar products and mixtures thereof.

[0060] The said additional organic solvents can be present inproportions preferably approximately ranging from 0.5 to 40% by weightrelative to the total weight of the dye composition, and even morepreferably approximately from 1 to 20% by weight.

[0061] The pH of the dye composition in accordance with the inventiongenerally approximately ranges from 2 to 11, and preferablyapproximately from 5 to 10 . It can be adjusted to the desired valueusing acidifying or basifying agents usually used for dyeing keratinfibers.

[0062] Among the acidifying agents which may be mentioned, for example,are inorganic or organic acids such as hydrochloric acid,orthophosphoric acid, sulphuric acid, carboxylic acids such as aceticacid, tartaric acid, citric acid or lactic acid, and sulphonic acids.

[0063] Among the basifying agents which may be mentioned, for example,are aqueous ammonia, alkaline carbonates, alkanolamines such as mono-,di- and triethanolamine and derivatives thereof, sodium hydroxide,potassium hydroxide and the compounds of formula (II) below:

[0064] in which W is a propylene residue optionally having a substituentchosen from a hydroxyl group and C₁-C₆ alkyl radicals; R₁₆, R₁₇, R₁₈ andR₁₉, which may be identical or different, are chosen from a hydrogenatom and C₁-C₆ alkyl and C₁-C₆ hydroxyalkyl radicals.

[0065] In addition to the cationic direct dye(s) defined above, the dyecomposition in accordance with the invention can contain one or moreadditional direct dyes which may be chosen, for example, fromnitrobenzene dyes, anthraquinone dyes, naphthoquinone dyes,triarylmethane dyes, xanthene dyes and azo dyes which are non-cationic.

[0066] When it is intended for oxidation dyeing, in addition to thecationic direct dye(s) and glycerol and/or specific polyol and/or polyolether defined above, the dye composition in accordance with theinvention contains one or more oxidation bases chosen from the oxidationbases conventionally used for oxidation dyeing and among which mentionmay be made in particular of para-phenylenediamines,bis(phenyl)alkylenediamines, para-aminophenols, ortho-aminophenols andheterocyclic bases.

[0067] When it is (they are) used, the oxidation base(s) preferablyrepresent(s) from 0.0005 to 12% by weight approximately relative to thetotal weight of the dye composition, and even more preferably from 0.005to 6% by weight approximately relative to this weight.

[0068] When it is intended for oxidation dyeing, in addition to thecationic direct dye and glycerol and/or specific polyol and/or polyolether defined above as well as oxidation bases, the dye composition inaccordance with the invention can also contain one or more couplers soas to modify or enrich with glints the shades obtained using thecationic direct dye(s) and the oxidation bases.

[0069] The couplers which can be used in the dye composition inaccordance with the invention can be chosen from the couplers usedconventionally in oxidation dyeing and among which mention may be madein particular of meta-phenylenediamines, meta-aminophenols,meta-diphenols and heterocyclic couplers.

[0070] When it is (they are) present, the coupler(s) preferablyrepresent(s) from 0.0001 to 10% by weight approximately relative to thetotal weight of the dye composition, and even more preferably from 0.005to 5% by weight approximately relative to this weight.

[0071] The dye composition in accordance with the invention can alsocontain various adjuvants conventionally used in compositions for dyeingthe hair, such as antioxidants, penetrating agents, sequestering agents,fragrances, buffers, dispersing agents, surfactants, film-formingagents, ceramides, preserving agents, screening agents and opacifiers.

[0072] Needless to say, a person skilled in the art will take care toselect this or these optional complementary compound(s) such that theadvantageous properties intrinsically associated with the dyecomposition in accordance with the invention are not, or are notsubstantially, adversely affected by the addition(s) envisaged.

[0073] The dye composition according to the invention can be in variousforms, such as in the form of liquids, shampoos, creams or gels or anyother form which is suitable for dyeing keratin fibers, and inparticular human hair. It can be obtained by mixing, at the time of use,a composition, which may be in pulverulent form, containing the cationicdirect dye(s) with a composition containing the glycerol and/or thespecific polyol and/or polyol ether.

[0074] When the combination of the cationic direct dye and glyceroland/or specific polyol and/or polyol ether defined according to theinvention is used in a composition intended for oxidation dyeing (one ormore oxidation bases are then used, optionally in the presence of one ormore couplers), or when it is used in a composition intended forlightening direct dyeing, then the dye composition in accordance withthe invention also contains at least one oxidizing agent chosen, forexample, from hydrogen peroxide, urea peroxide, alkali metal bromates,persalts such as perborates and persulphates, and enzymes such asperoxidases, laccases and two-electron oxidoreductases. The use ofhydrogen peroxide or enzymes is particularly preferred.

[0075] Another subject of the invention is a process for dyeing keratinfibers, and in particular human keratin fibers such as the hair, usingthe dye composition as defined above.

[0076] According to a first variant of this dyeing process in accordancewith the invention, at least one dye composition as defined above isapplied to the fibers, for a period which is sufficient to develop thedesired coloration, after which the fibers are rinsed, optionally washedwith shampoo, rinsed again and dried.

[0077] The time required to develop the coloration on the keratin fibersgenerally ranges from 3 to 60 minutes and even more preferably from 5 to40 minutes.

[0078] According to a second variant of this dyeing process inaccordance with the invention, at least one dye composition as definedabove is applied to the fibers, for a period which is sufficient todevelop the desired coloration, without final rinsing.

[0079] According to one specific embodiment of this dyeing process, andwhen the dye composition in accordance with the invention contains atleast one oxidation base and at least one oxidizing agent, the dyeingprocess includes a preliminary step which comprises separately storing,on the one hand, a composition (A1) comprising, in a medium which issuitable for dyeing, at least one cationic direct dye and at leastglycerol and/or one specific polyol and/or polyol ether as defined aboveand at least one oxidation base, and, on the other hand, a composition(B1) containing, in a medium which is suitable for dyeing, at least oneoxidizing agent, and then in mixing them together at the time of use,after which this mixture is applied to the keratin fibers.

[0080] According to another specific embodiment of this dyeing process,and when the dye composition in accordance with the invention containsat least one oxidizing agent, the dyeing process includes a preliminarystep which comprises separately storing, on the one hand, a composition(A2) comprising, in a medium which is suitable for dyeing, at least onecationic direct dye and at least glycerol and/or one specific polyoland/or polyol ether as defined above, and, on the other hand, acomposition (B1) containing, in a medium which is suitable for dyeing,at least one oxidizing agent, and then in mixing them together at thetime of use, after which this mixture is applied to the keratin fibers.

[0081] Another subject of the invention is a multi-compartment dyeingdevice or “kit” or any other multi-compartment packaging system, a firstcompartment of which comprises composition (A1) or (A2) as defined aboveand a second compartment of which comprises composition (B1) as definedabove. These devices can be equipped with means for delivering thedesired mixture onto the hair, such as the devices described in patentFR 2,586,913, assigned to the present assignee.

[0082] The examples which follow are intended to illustrate theinvention without, however, limiting its scope.

EXAMPLES Example 1

[0083] The dye composition below was prepared: Cationic direct dye offormula (I)₂₇ 0.1 g Glycerol 10.0 g 2-Amino-2-methylpropanol qs pH9Demineralized water qs 100 g

[0084] The above composition was applied for 30 minutes to locks ofnatural grey hair containing 90% white hairs. The locks of hair werethen rinsed, washed with a standard shampoo and then dried.

[0085] They were dyed in an intense purple shade.

Example 2

[0086] The dye composition below was prepared: Cationic direct dye offormula (I)₁₀ 0.12 g Propylene glycol monomethyl ether 10.0 g2-Amino-2-methylpropanol qs pH9 Demineralized water qs 100 g

[0087] The above composition was applied for 30 minutes to locks ofnatural grey hair containing 90% white hairs. The locks of hair werethen rinsed, washed with a standard shampoo and then dried.

[0088] They were dyed in an intense red shade.

What is claimed is:
 1. A composition for dyeing keratin fiberscomprising: (i) at least one cationic direct dye of formula (I) below:A—N═N—B  (I) in which: the symbol A represents a group chosen fromstructures A₁ to A₃ below:

in which structures A₁ to A₃, R₁ is chosen from C₁-C₄ alkyl radicals anda phenyl radical having a substituent chosen from C₁-C₄ alkyl radicalsand halogen atoms chosen from chlorine, bromine, iodine and fluorine; R₂is chosen from C₁-C₄ alkyl radicals and a phenyl radical; R₃ and R₄,which may be identical or different, are chosen from C₁-C₄ alkylradicals and a phenyl radical or, in the case of structure A₁, cantogether form a substituted benzene ring, and in the case of structureA₂, can together form a benzene ring optionally having at least onesubstituent chosen from C₁-C₄ alkyl, C₁-C₄ alkoxy and NO₂ radicals; R₃can also denote a hydrogen atom; Z is chosen from an oxygen atom, asulphur atom, and —NR₂ groups; M is chosen from —CH, —CR, where R ischosen from C₁-C₄ alkyl radicals, and —N⁺R₅(X⁻)_(r) groups; K is chosenfrom —CH, —CR, where R is chosen from C₁-C₄ alkyl radicals, and—N⁺R₅(X⁻)_(r) groups; P is chosen from —CH, —CR, where R is chosen fromC₁-C₄ alkyl radicals, and —N⁺R₅(X⁺)_(r) groups; r denotes 0 or 1; R₅ ischosen from an atom O⁻, C₁-C₄ alkoxy radicals and C₁-C₄ alkyl radicals;R₆ and R₇, which may be identical or different, are chosen from ahydrogen atom, halogen atoms chosen from chlorine, bromine, iodine andfluorine, C₁-C₄ alkyl radicals, C₁-C₄ alkoxy radicals and an —NO₂radical; X⁻ is an anion; with the proviso that, if R₄ is a C₁-C₄ alkylradical and Z is a sulphur atom, R₃ is not a hydrogen atom; if R₅ is O⁻,then r is zero; if K or P or M is —N⁺—C₁-C₄ -alkyl X⁻, then R₆ or R₇ isother than a hydrogen atom; if K is —N⁺R₅(X⁻)_(r), then M═P and is —CHor —CR; if M is —N⁺R₅(X⁻)_(r), then K═P and is —CH or —CR; if P is—N⁺R₅(X⁻)_(r), then K═M and is —CH or —CR; if Z is —NR₂ and R₂ is aC₁-C₄ alkyl radical, then at least one of the radicals R₁, R₃ or R₄ ofstructure A₂ is other than a C₁-C₄ alkyl radical; the symbol Brepresents: (a) a group of structure B₁ below:

in which structure B₁, R₈ is chosen from a hydrogen atom, halogen atomschosen from chlorine, bromine, iodine and fluorine, C₁-C₄ alkylradicals, C₁-C₄ alkoxy radicals, a radical —OH, a radical —NO₂, —NHR₁₁radicals, —NR₁₂R₁₃ radicals, and —NHCO(C₁-C₄)alkyl radicals or forms,with R₉, a 5- or 6-membered ring which may contain at least one heteroatom chosen from nitrogen, oxygen and sulphur; R₉ is chosen from ahydrogen atom, halogen atoms chosen from chlorine, bromine, iodine andfluorine, C₁-C₄ alkyl radicals, and C₁-C₄ alkoxy radicals, or forms,with R₁₀ or R₁₁, a 5- or 6-membered ring which may contain at least onehetero atom chosen from nitrogen, oxygen and sulphur; R₁₀ is chosen froma hydrogen atom, an —OH radical, —NHR₁₁ radicals and —NR₁₂R₁₃ radicals;R₁₁ is chosen from a hydrogen atom, C₁-C₄ alkyl radicals, C₁-C₄monohydroxyalkyl radicals, C₂-C₄ polyhydroxyalkyl radicals and a phenylradical; R₁₂ and R₁₃, which may be identical or different, are chosenfrom C₁-C₄ alkyl radicals, C₁-C₄ monohydroxyalkyl radicals and C₂-C₄polyhydroxyalkyl radicals; or (b) a 5- or 6-membered nitrogenousheterocyclic group which can contain at least one other hetero atomand/or at least one carbonyl group and which can have at least onesubstituent chosen from C₁-C₄ alkyl, amino and phenyl radicals, and (ii)at least one compound chosen from glycerol, polyols containing at least4 carbon atoms, C₁-C₈ aliphatic ethers of C₃-C₉ polyols, and C₆-C₈aromatic ethers of C₂-C₉ polyols.
 2. The composition according to claim1, wherein, in formula (I), the C₁-C₄ alkyl radicals are chosen frommethyl, ethyl, and butyl radicals and the C₁-C₄ alkoxy radicals aremethoxy and ethoxy radicals.
 3. The composition according to claim 1,wherein the symbol B represents a a group of structure B₂ below:

in which structure B₂, R₁₄ and R₁₅, which may be identical or different,are chosen from a hydrogen atom, C₁-C₄ alkyl radicals and a phenylradical; Y is chosen from a —CO— radical and a radical

n=0 or 1, where, when n is 1, U is a —CO— radical.
 4. The compositionaccording to claim 1, wherein X⁻ is chosen from chloride, iodide, methylsulphate, ethyl sulphate, acetate and perchlorate.
 5. The compositionaccording to claim 1, wherein said keratin fibers are human keratinfibers.
 6. The composition according to claim 5, wherein said humankeratin fibers are hair.
 7. The composition according to claim 1,wherein said polyols containing at least 4 carbon atoms are chosen fromC₄-C₉ polyols and polyalkylene glycols.
 8. The composition according toclaim 7, wherein said polyalkylene glycols are chosen from polyethyleneglycols and polypropylene glycols.
 9. The composition according to claim7, wherein said C₄-C₉ polyols are chosen from 2-butene-1,4-diolpentane-1,5-diol, 2,2-dimethylpropane-1,3-diol,3-methylpentane-1,5-diol, pentane-1,2-diol,2,2,4-trimethylpentane-1,3-diol, 2-methylpropane-1,3-diol, hexyleneglycol, 1,3-butylene glycol, dipropylene glycol, diethylene glycol andtriethylene glycol.
 10. The composition according to claim 1, whereinsaid C₁-C₈ aliphatic ethers of C₃-C₉ polyols are chosen from propyleneglycol monomethyl ether, propylene glycol monoethyl ether, isopropyleneglycol dimethyl ether, diethylene glycol monomethyl ether and monoethylether, dipropylene glycol monomethyl ether, tripropylene glycolmonomethyl ether and diethylene glycol dimethyl ether.
 11. Thecomposition according to claim 1, wherein said C₆-C₈ aromatic ethers ofC₂-C₉ polyols are chosen from ethylene glycol monophenyl ether, ethyleneglycol monobenzyl ether, propylene glycol monophenyl ether, propyleneglycol monobenzyl ether, diethylene glycol monophenyl ether anddiethylene glycol monobenzyl ether.
 12. The composition according toclaim 1, wherein said at least one cationic direct dye is chosen fromstructures (I)₁ to (I)₇₇ below:


13. The composition according to claim 1, wherein said at least onecationic direct dye of formula (I) is present in an amount ranging from0.001 to 10% by weight relative to the total weight of the composition.14. The composition according to claim 13, wherein said at least onecationic direct dye of formula (I) is present in an amount ranging from0.005 to 5% by weight relative to the total weight of the composition.15. The composition according to claim 1, wherein said at least onecompound chosen from glycerol, polyols containing at least 4 carbonatoms, C₁-C₈ aliphatic, ethers of C₃-C₉ polyols and C₆-C₈ aromaticethers of C₂-C₉ polyols is present in an amount ranging from 0.1 to 40%by weight relative to the total weight of the composition.
 16. Thecomposition according to claim 15, wherein said at least one compound ispresent in an amount ranging from 0.5 to 20% by weight relative to thetotal weight of the composition.
 17. The composition according to claim1, wherein said composition further comprises additional direct dyes.18. The composition according to claim 1, wherein said compositionfurther comprises a mixture of water and at least one solvent chosenfrom glycerol, polyols containing at least 4 carbon atoms, C₁-C₈aliphatic ethers of C₃-C₈ polyols, and C₆-C₈ aromatic ethers of C₂-C₉polyols.
 19. The composition according to claim 18, wherein saidcomposition further comprises at least one additional organic solvent.20. The composition according to claim 1, wherein said composition has apH ranging from 2 to
 11. 21. The composition according to claim 20,wherein said pH ranges from 5 to
 10. 22. The composition according toclaim 1, wherein said composition further comprises at least oneoxidation base chosen from para-phenylenediamines,bis(pheniyl)alkylenediamines, para-aminophenols, ortho-aminophenols andheterocyclic bases.
 23. The composition according to claim 22, whereinsaid at least on e oxidation base is present in an amount ranging from0.0005 to 12% by weight relative to the total weight of the composition.24. The composition according to claim 23, wherein said at least oneoxidation base is present in an amount ranging from 0.005 to 6% byweight relative to the total weight of the composition.
 25. Thecomposition according to claim 22, wherein said composition furthercomprises at least one coupler chosen from meta-phenylenediamine,meta-aminophenols, meta-diphenols and heterocyclic couplers.
 26. Thecomposition according to claim 25, wherein said at least one coupler ispresent in an amount ranging from 0.0001 to 10% by weight relative tothe total weight of the composition.
 27. The composition according toclaim 26, wherein said at least one coupler is present in an amountranging from 0.005 to 5% by weight relative to the total weight of thecomposition.
 28. The composition according to claim 1, wherein saidcomposition further comprises at least one oxidizing agent.
 29. Aprocess for dyeing keratin fibers, comprising applying to said fibers,for a period which is sufficient to develop the desired coloration, atleast one dye composition comprising: (i) at least one cationic directdye of formula (I) below: A—N═N—B  (I) in which: the symbol A representsa group chosen from structures A₁ to A₃ below:

in which structures A₁ to A₃, R₁ is chosen from C₁-C₄ alkyl radicals anda phenyl radical having a substituent chosen from C₁-C₄ alkyl radicalsand halogen atoms chosen from chlorine, bromine, iodine and fluorine; R₂is chosen from C₁-C₄ alkyl radicals and a phenyl radical; R₃ and R₄,which may be identical or different, are chosen from C₁-C₄ alkylradicals and a phenyl radical or, in the case of structure A₁, cantogether form a substituted benzene ring, and in the case of structureA₂, can together form a benzene ring optionally having at least onesubstituent chosen from C₁-C₄ alkyl, C₁-C₄ alkoxy and NO₂ radicals; R₃can also denote a hydrogen atom; Z is chosen from an oxygen atom, asulphur atom, and —NR₂ groups; M is chosen from —CH, —CR, where R ischosen from C₁-C₄ alkyl radicals, and —N⁺R₅(X⁻)_(r) groups; K is chosenfrom —CH, —CR, where R is chosen from C₁-C₄ alkyl radicals, and—N⁺R₅(X⁻)_(r) groups; P is chosen from —CH, —CR, where R is chosen fromC₁-C₄ alkyl radicals, and —N⁺R₅(X⁻)_(r) groups; r denotes 0 or 1; R₅ ischosen from an atom O⁻, C₁-C₄ alkoxy radicals and C₁-C₄ alkyl radicals;R₆ and R₇, which may be identical or different, are chosen from ahydrogen atom, halogen atoms chosen from chlorine, bromine, iodine andfluorine, C₁-C₄ alkyl radicals, C₁-C₄ alkoxy radicals and an —NO₂radical; X⁻ is an anion; with the proviso that, if R₄ is a C₁-C₄ alkylradical and Z is a sulphur atom, R₃ is not a hydrogen atom; if R₅ is O⁻,then r is zero; if K or P or M is —N⁺C₁-C₄ -alkyl X⁻, then R₆ or R₇ isother than a hydrogen atom; if K is —N⁺R₅(X⁻)_(r), then M═P and is —CHor —CR; if M is —N⁺R₅(X⁻)_(r), then K═P and is —CH or —CR; if P is—N⁺R₅(X⁻)_(r), then K═M and is —CH or —CR; if Z is —NR₂ and R₂ is aC₁-C₄ alkyl radical, then at least one of the radicals R₁, R₃ or R₄ ofstructure A₂ is other than a C₁-C₄ alkyl radical; the symbol Brepresents: (a) a group of structure B₁ below:

in which structure B₁, R₈ is chosen from a hydrogen atom, halogen atomschosen from chlorine, bromine, iodine and fluorine, C₁-C₄ alkylradicals, C₁-C₄ alkoxy radicals, a radical —OH, a radical —NO₂, —NHR₁₁radicals, —NR₁₂R₁₃ radicals, and —NHCO(C₁-C₄)alkyl radicals or forms,with R₉, a 5- or 6-membered ring which may contain at least one heteroatom chosen from nitrogen, oxygen and sulphur; R₉ is chosen from ahydrogen atom, halogen atoms chosen from chlorine, bromine, iodine andfluorine, C₁-C₄ alkyl radicals, and C₁-C₄ alkoxy radicals, or forms,with R₁₀ or R₁₁, a 5- or 6-membered ring which may contain at least onehetero atom chosen from nitrogen, oxygen and sulphur; R₁₀ is chosen froma hydrogen atom, an —OH radical, —NHR₁₁ radicals and —NR₁₂R₁₃ radicals;R₁₁ is chosen from a hydrogen atom, C₁-C₄ alkyl radicals, C₁-C₄monohydroxyalkyl radicals, C₂-C₄ polyhydroxyalkyl radicals and a phenylradical; R₁₂ and R₁₃, which may be identical or different, are chosenfrom C₁-C₄ alkyl radicals, C₁-C₄ monohydroxyalkyl radicals and C₂-C₄polyhydroxyalkyl radicals; or (b) a 5- or 6-membered nitrogenousheterocyclic group which can contain at least one other hetero atomand/or at least one carbonyl group and which can have at least onesubstituent chosen from C₁-C₄ alkyl, amino and phenyl radicals, and (ii)at least one compound chosen from glycerol, polyols containing at least4 carbon atoms, C₁-C₈ aliphatic ethers of C₃-C₉ polyols, and C₆-C₈aromatic ethers of C₂-C₉ polyols, rinsing the fibers, optionally washingsaid fibers with shampoo and rinsing again, and drying.
 30. A processfor dyeing keratin fibers according to claim 29, wherein said keratinfibers are human keratin fibers.
 31. A process for dyeing keratin fibersaccording to claim 30, wherein said human keratin fibers are hair.
 32. Aprocess for dyeing keratin fibers according to claim 29, wherein saidfibers are not rinsed a second time before drying.
 33. A process fordyeing keratin fibers comprising: separately storing a first compositioncomprising: (i) at least one cationic direct dye of formula (I) below:A—N═N—B  (I) in which: the symbol A represents a group chosen fromstructures A₁ to A₃ below:

in which structures A₁ to A₃, R₁ is chosen from C₁-C₄ alkyl radicals anda phenyl radical having a substituent chosen from C₁-C₄ alkyl radicalsand halogen atoms chosen from chlorine, bromine, iodine and fluorine; R₂is chosen from C₁-C₄ alkyl radicals and a phenyl radical; R₃ and R₄,which may be identical or different, are chosen from C₁-C₄ alkylradicals and a phenyl radical or, in the case of structure A₁, cantogether form a substituted benzene ring, and in the case of structureA₂, can together form a benzene ring optionally having at least onesubstituent chosen from C₁-C₄ alkyl, C₁-C₄ alkoxy and NO₂ radicals; R₃can also denote a hydrogen atom; Z is chosen from an oxygen atom, asulphur atom, and —NR₂ groups; M is chosen from —CH, —CR, where R ischosen from C₁-C₄ alkyl radicals, and —N⁺R₅(X⁻)_(r) groups; K is chosenfrom —CH, —CR, where R is chosen from C₁-C₄ alkyl radicals, and—N⁺R₅(X⁻)_(r) groups; P is chosen from —CH, —CR, where R is chosen fromC₁-C₄ alkyl radicals, and —N⁺R₅(X⁻)_(r) groups; r denotes 0 or 1; R₅ischosen from an atom O⁻, C₁-C₄ alkoxy radicals and C₁-C₄ alkyl radicals;R₆ and R₇, which may be identical or different, are chosen from ahydrogen atom, halogen atoms chosen from chlorine, bromine, iodine andfluorine, C₁-C₄ alkyl radicals, C₁-C₄ alkoxy radicals and an —NO₂radical; X⁻ is an anion; with the proviso that, if R₄is a C₁-C₄ alkylradical and Z is a sulphur atom, R₃is not a hydrogen atom; if R₅ is O⁻,then r is zero; if K or P or M is —N⁺-C₁-C₄ -alkyl X⁻, then R₆ or R₇ isother than a hydrogen atom; if K is —N⁺R₅(X⁻)_(r), then M═P and is —CHor —CR; if M is —N⁺R₅(X⁻)_(r), then K═P and is —CH or —CR; if P is—N⁺R₅(X⁻)_(r), then K═M and is —CH or —CR; if Z is —NR₂ and R₂ is aC₁-C₄ alkyl radical, then at least one of the radicals R₁, R₃ or R₄ ofstructure A₂ is other than a C₁-C₄ alkyl radical; the symbol Brepresents: (a) a group of structure B₁ below:

in which structure B₁, R₈ is chosen from a hydrogen atom, halogen atomschosen from chlorine, bromine, iodine and fluorine, C₁-C₄ alkylradicals, C₁-C₄ alkoxy radicals, a radical —OH, a radical —NO₂, —NHR₁₁radicals, —NR₁₂R₁₃ radicals, and —NHCO(C₁-C₄)alkyl radicals or forms,with R₉, a 5- or 6-membered ring which may contain at least one heteroatom chosen from nitrogen, oxygen and sulphur; R₉ is chosen from ahydrogen atom, halogen atoms chosen from chlorine, bromine, iodine andfluorine, C₁-C₄ alkyl radicals, and C₁-C₄ alkoxy radicals, or forms,with R₁₀ or R₁₁, a 5- or 6-membered ring which may contain at least onehetero atom chosen from nitrogen, oxygen and sulphur; R₁₀ is chosen froma hydrogen atom, an —OH radical, —NHR₁₁ radicals and —NR₁₂R₁₃ radicals;R₁₁ is chosen from a hydrogen atom, C₁-C₄ alkyl radicals, C₁-C₄monohydroxyalkyl radicals, C₂-C₄ polyhydroxyalkyl radicals and a phenylradical; R₁₂ and R₁₃, which may be identical or different, are chosenfrom C₁-C₄ alkyl radicals, C₁-C₄ monohydroxyalkyl radicals and C₂-C₄polyhydroxyalkyl radicals; or (b) a 5- or 6-membered nitrogenousheterocyclic group which can contain at least one other hetero atomand/or at least one carbonyl group and which can have at least onesubstituent chosen from C₁-C₄ alkyl, amino and phenyl radicals, (ii) atleast one compound chosen from glycerol, polyols containing at least 4carbon atoms, C₁-C₈ aliphatic ethers of C₃-C₉ polyols, and C₆-C₈aromatic ethers of C₂-C₉ polyols, and (iii) at least one oxidation base,separately storing a second composition comprising at least oneoxidizing agent, and thereafter mixing said first composition with saidsecond composition and applying this mixture to said keratin fibers. 34.A process for dyeing keratin fibers comprising: separately storing afirst composition comprising (i) at least one cationic direct dye offormula (I) below: A—N═N—B  (I) in which: the symbol A represents agroup chosen from structures A₁ to A₃ below:

in which structures A₁ to A₃, R₁ is chosen from C₁-C₄ alkyl radicals anda phenyl radical having a substituent chosen from C₁-C₄ alkyl radicalsand halogen atoms chosen from chlorine, bromine, iodine and fluorine; R₂is chosen from C₁-C₄ alkyl radicals and a phenyl radical; R₃ and R₄,which may be identical or different, are chosen from C₁-C₄ alkylradicals and a phenyl radical or, in the case of structure A₁, cantogether form a substituted benzene ring, and in the case of structureA₂, can together form a benzene ring optionally having at least onesubstituent chosen from C₁-C₄ alkyl, C₁-C₄ alkoxy and NO₂ radicals; R₃can also denote a hydrogen atom; Z is chosen from an oxygen atom, asulphur atom, and —NR₂ groups; M is chosen from —CH, —CR, where R ischosen from C₁-C₄ alkyl radicals, and —N⁺R₅(X⁻)_(r) groups; K is chosenfrom —CH, —CR, where R is chosen from C₁-C₄ alkyl radicals, and—N⁺R₅(X⁻)_(r) groups; P is chosen from —CH, —CR, where R is chosen fromC₁-C₄ alkyl radicals, and —N⁺R₅(X⁻)_(r) groups; r denotes 0 or 1; R₅ ischosen from an atom O⁻, C₁-C₄ alkoxy radicals and C₁-C₄ alkyl radicals;R₆ and R₇, which may be identical or different, are chosen from ahydrogen atom, halogen atoms chosen from chlorine, bromine, iodine andfluorine, C₁-C₄ alkyl radicals, C₁-C₄ alkoxy radicals and an —NO₂radical; X⁻ is an anion; with the proviso that, if R₄ is a C₁-C₄ alkylradical and Z is a sulphur atom, R₃ is not a hydrogen atom; if R₅ is O⁻,then r is zero; if K or P or M is —N⁺-C₁-C₄ -alkyl X⁻, then R₆ or R₇ isother than a hydrogen atom; if K is —N⁺R₅(X⁻)_(r), then M═P and is —CHor —CR; if M is —N⁺R₅(X⁻)_(r), then K═P and is —CH or —CR; if P is—N⁺R₅(X⁻)_(r), then K═M and is —CH or —CR; if Z is —NR₂ and R₂ is aC₁-C₄ alkyl radical, then at least one of the radicals R₁, R₃ or R₄ ofstructure A₂ is other than a C₁-C₄ alkyl radical; the symbol Brepresents: (a) a group of structure B₁ below:

in which structure B₁, R₈ is chosen from a hydrogen atom, halogen atomschosen from chlorine, bromine, iodine and fluorine, C₁-C₄ alkylradicals, C₁-C₄ alkoxy radicals, a radical —OH, a radical —NO₂, —NHR₁₁radicals, —NR₁₂R₁₃ radicals, and —NHCO(C₁-C₄)alkyl radicals or forms,with R₉, a 5- or 6-membered ring which may contain at least one heteroatom chosen from nitrogen, oxygen and sulphur; R₉ is chosen from ahydrogen atom, halogen atoms chosen from chlorine, bromine, iodine andfluorine, C₁-C₄ alkyl radicals, and C₁-C₄ alkoxy radicals, or forms,with R₁₀ or R₁₁, a 5- or 6-membered ring which may contain at least onehetero atom chosen from nitrogen, oxygen and sulphur; R₁₀ is chosen froma hydrogen atom, an —OH radical, —NHR₁₁ radicals and —NR₁₂R₁₃ radicals;R₁₁ is chosen from a hydrogen atom, C₁-C₄ alkyl radicals, C₁-C₄monohydroxyalkyl radicals, C₂-C₄ polyhydroxyalkyl radicals and a phenylradical; R₁₂ and R₁₃, which may be identical or different, are chosenfrom C₁-C₄ alkyl radicals, C₁-C₄ monohydroxyalkyl radicals and C₂-C₄polyhydroxyalkyl radicals; or (b) a 5- or 6-membered nitrogenousheterocyclic group which can contain at least one other hetero atomand/or at least one carbonyl group and which can have at least onesubstituent chosen from C₁-C₄ alkyl, amino and phenyl radicals, and (ii)at least one compound chosen from glycerol, polyols containing at least4 carbon atoms, C₁-C₈ aliphatic ethers of C₃-C₉ polyols, and C₆-C₈aromatic ethers of C₂-C₉ polyols, separately storing a secondcomposition comprising at least one oxidizing agent, and thereaftermixing said first composition with said second composition and applyingthis mixture to said keratin fibers.
 35. A multi-compartment dyeingdevice or multi-compartment dyeing kit compnsing at least two separatecompartments, wherein a first compartment contains a com positioncomprising: in which: the symbol A represents a group chosen fromstructures A₁ to A₃ below:

in which structures A₁ to A₃, R₁ is chosen from C₁-C₄ alkyl radicals anda phenyl radical having a substituent chosen from C₁-C₄ alkyl radicalsand halogen atoms chosen from chlorine, bromine, iodine and fluorine; R₂is chosen from C₁-C₄ alkyl radicals and a phenyl radical; R₃ and R₄,which may be identical or different, are chosen from C₁-C₄ alkylradicals and a phenyl radical or, in the case of structure A₁, cantogether form a substituted benzene ring, and in the case of structureA₂, can together form a benzene ring optionally having at least onesubstituent chosen from C₁-C₄ alkyl, C₁-C₄ alkoxy and NO₂ radicals; R₃can also denote a hydrogen atom; Z is chosen from an oxygen atom, asulphur atom, and —NR₂ groups; M is chosen from —CH, —CR, where R ischosen from C₁-C₄ alkyl radicals, and —N⁺R₅(X⁻)_(r) groups; K is chosenfrom —CH, —CR, where R is chosen from C₁-C₄ alkyl radicals, and—N⁺R₅(X⁻)_(r) groups; P is chosen from —CH, —CR, where R is chosen fromC₁-C₄ alkyl radicals, and —N⁺R₅(X⁻)_(r) groups; r denotes 0 or 1; R₅ ischosen from an atom O⁻, C₁-C₄ alkoxy radicals and C₁-C₄ alkyl radicals;R⁶ and R₇, which may be identical or different, are chosen from ahydrogen atom, halogen atoms chosen from chlorine, bromine, iodine andfluorine, C₁-C₄ alkyl radicals, C₁-C₄ alkoxy radicals and an —NO₂radical; X⁻ is an anion; with the proviso that, if R₄ is a C₁-C₄ alkylradical and Z is a sulphur atom, R₃ is not a hydrogen atom; if R₅ is O⁻,then r is zero; if K or P or M is —N⁺-C₁-C₄ -alkyl X⁻, then R₆ or R₇ isother than a hydrogen atom; if K is —N⁺R₅(X⁻)_(r), then M═P and is —CHor —CR; if M is —N⁺R₅(X⁻)_(r), then K═P and is —CH or —CR; if P is—N⁺R₅(X⁻)_(r), then K═M and is —CH or —CR; if Z is —NR₂ and R₂ is aC₁-C₄ alkyl radical, then at least one of the radicals R₁, R₃ or R₄ ofstructure A₂ is other than a C₁-C₄ alkyl radical; the symbol Brepresents: (a) a group of structure B₁ below:

in which structure B₁, R₈ is chosen from a hydrogen atom, halogen atomschosen from chlorine, bromine, iodine and fluorine, C₁-C₄ alkylradicals, C₁-C₄ alkoxy radicals, a radical —OH, a radical —NO₂, —NHR₁₁radicals, —NR₁₂R₁₃ radicals, and —NHCO(C₁-C₄)alkyl radicals or forms,with R₉, a 5- or 6-membered ring which may contain at least one heteroatom chosen from nitrogen, oxygen and sulphur; R₉ is chosen from ahydrogen atom, halogen atoms chosen from chlorine, bromine, iodine andfluorine, C₁-C₄ alkyl radicals, and C₁-C₄ alkoxy radicals, or forms,with R₁₀ or R₁₁, a 5- or 6-membered ring which may contain at least onehetero atom chosen from nitrogen, oxygen and sulphur; R₁₀ is chosen froma hydrogen atom, an —OH radical, —NHR₁₁ radicals and —NR₁₂R₁₃ radicals;R₁₁ is chosen from a hydrogen atom, C₁-C₄ alkyl radicals, C₁-C₄monohydroxyalkyl radicals, C₂-C₄ polyhydroxyalkyl radicals and a phenylradical; R₁₂ and R₁₃, which may be identical or different, are chosenfrom C₁-C₄ alkyl radicals, C₁-C₄ monohydroxyalkyl radicals and C₂-C₄polyhydroxyalkyl radicals; or (b) a 5- or 6-membered nitrogenousheterocyclic group which can contain at least one other hetero atomand/or at least one carbonyl group and which can have at least onesubstituent chosen from C₁-C₄ alkyl, amino and phenyl radicals, (ii) atleast one compound chosen from glycerol, polyols containing at least 4carbon atoms, C₁-C₈ aliphatic ethers of C₃-C₉ polyols, and C₆-C₈aromatic ethers of C₂-C₉ polyols, and (iii) at least one oxidation base,and a second compartment contains a composition comprising at least oneoxidizing agent.
 36. A multi-compartment dyeing device ormulti-compartment dyeing kit comprising at least two separatecompartments wherein a first compartment contains a compositioncomprising: in which: the symbol A represents a group chosen fromstructures A₁ to A₃ below:

in which structures A₁ to A₃, R₁ is chosen from C₁-C₄ alkyl radicals anda phenyl radical having a substituent chosen from C₁-C₄ alkyl radicalsand halogen atoms chosen from chlorine, bromine, iodine and fluorine; R₂is chosen from C₁-C₄ alkyl radicals and a phenyl radical; R₃ and R₄,which may be identical or different, are chosen from C₁-C₄ alkylradicals and a phenyl radical or, in the case of structure A₁, cantogether form a substituted benzene ring, and in the case of structureA₂, can together form a benzene ring optionally having at least onesubstituent chosen from C₁-C₄ alkyl, C₁-C₄ alkoxy and NO₂ radicals; R₃can also denote a hydrogen atom; Z is chosen from an oxygen atom, asulphur atom, and —NR₂ groups; M is chosen from —CH, —CR, where R ischosen from C₁-C₄ alkyl radicals, and —N⁺R₅(X⁻)_(r) groups; K is chosenfrom —CH, —CR, where R is chosen from C₁-C₄ alkyl radicals, and—N⁺R₅(X⁻)_(r) groups; P is chosen from —CH, —CR, where R is chosen fromC₁-C₄ alkyl radicals, and —N⁺R₅(X⁻)_(r) groups; r denotes 0 or 1; R₅ ischosen from an atom O⁻, C₁-C₄ alkoxy radicals and C₁-C₄ alkyl radicals;R₆ and R₇, which may be identical or different, are chosen from ahydrogen atom, halogen atoms chosen from chlorine, bromine, iodine andfluorine, C₁-C₄ alkyl radicals, C₁-C₄ alkoxy radicals and an —NO₂radical; X⁻ is an anion; with the proviso that, if R₄ is a C₁-C₄ alkylradical and Z is a sulphur atom, R₃ is not a hydrogen atom; if R₅ is O⁻,then r is zero; if K or P or M is —N⁺C₁-C₄ -alkyl X⁻, then R₆ or R₇ isother than a hydrogen atom; if K is —N⁺R₅(X⁻)_(r), then M═P and is —CHor —CR; if M is —N⁺R₅(X⁻)_(r), then K═P and is —CH or —CR; if P is—N⁺R₅(X⁻)_(r), then K═M and is —CH or —CR; if Z is —NR₂ and R₂ is aC₁-C₄ alkyl radical, then at least one of the radicals R₁, R₃ or R₄ ofstructure A₂ is other than a C₁-C₄ alkyl radical; the symbol Brepresents: (a) a group of structure B₁ below:

in which structure B₁, R₈ is chosen from a hydrogen atom, halogen atomschosen from chlorine, bromine, iodine and fluorine, C₁-C₄ alkylradicals, C₁-C₄ alkoxy radicals, a radical —OH, a radical —NO₂, —NHR₁₁radicals, —NR₁₂R₁₃ radicals, and —NHCO(C₁-C₄)alkyl radicals or forms,with R₉, a 5- or 6-membered ring which may contain at least one heteroatom chosen from nitrogen, oxygen and sulphur; R₉ is chosen from ahydrogen atom, halogen atoms chosen from chlorine, bromine, iodine andfluorine, C₁-C₄ alkyl radicals, and C₁-C₄ alkoxy radicals, or forms,with R₁₀ or R₁₁, a 5- or 6-membered ring which may contain at least onehetero atom chosen from nitrogen, oxygen and sulphur; R₁₀ is chosen froma hydrogen atom, an —OH radical, —NHR_(11,) radicals and —NR₁₂R₁₃radicals; R₁₁ is chosen from a hydrogen atom, C₁-C₄ alkyl radicals,C₁-C₄ monohydroxyalkyl radicals, C₂-C₄ polyhydroxyalkyl radicals and aphenyl radical; R₁₂ and R₁₃, which may be identical or different, arechosen from C₁-C₄ alkyl radicals, C₁-C₄ monohydroxyalkyl radicals andC₂-C₄ polyhydroxyalkyl radicals; or (b) a 5- or 6-membered nitrogenousheterocyclic group which can contain at least one other hetero atomand/or at least one carbonyl group and which can have at least onesubstituent chosen from C₁-C₄ alkyl, amino and phenyl radicals, and (ii)at least one compound chosen from glycerol, polyols containing at least4 carbon atoms, C₁-C₈ aliphatic ethers of C₃-C₉ polyols, and C₆-C₈aromatic ethers of C₂-C₉ polyols, and a second compartment contains acomposition comprising at least one oxidizing agent.